The following key changes applies to the Dec. 15, 1908 Patent #
907026.

Flat Key Changes

The mechanism could support 4x4x4-3x2=122 key changes, however only 12
off the shelf key changes
have been found on the numbered locks, and catalog advertisements state 12 key
changes. For an additional charge Fraim would sell the
other 110 key changes. Interestingly the depth cuts for key codes 61-66 were
duplicated for 67-72 where the key rib made the key code unique. The ILCO E375 or ILCO T127 blanks work well for this lock.

1) Smoke the key and locate the deep cut lever. This will also establish your
key spacing.
2) What I like to do now is
pick the lockso I may watch the levers as I make my depth
and spacing cuts.
This is not necessary but rather an aid in cutting the key.